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##=============================================================================##
##      context.S
##
##      CalmRISC16 context switch code
##
##=============================================================================
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##=============================================================================
#######DESCRIPTIONBEGIN####
##
## Author(s):   msalter
## Contributors: msalter
## Date:        2001-02-12
## Purpose:     CalmRISC16 context switch code
## Description: This file contains implementations of the thread context 
##              switch routines. It also contains the longjmp() and setjmp()
##              routines.
##
######DESCRIPTIONEND####
##
##=============================================================================

#include <pkgconf/hal.h>
#include <cyg/hal/arch.inc>

#------------------------------------------------------------------------------
# hal_thread_switch_context
# Switch thread contexts
# A0 = address of sp of next thread to execute
# A1 = address of sp save location of current thread

        .global hal_thread_switch_context
hal_thread_switch_context:              
        // FIXME        
        # Now load the destination thread by dropping through
        # to hal_thread_load_context
        
#------------------------------------------------------------------------------
# hal_thread_load_context
# Load thread context
# A0 = address of sp of next thread to execute
# Note that this function is also the second half of hal_thread_switch_context
# and is simply dropped into from it.
        
        .global hal_thread_load_context
hal_thread_load_context:
        // FIXME

#------------------------------------------------------------------------------
# HAL longjmp, setjmp implementations
# hal_setjmp saves only callee save registers into given buffer
# Note: These definitions are repeated in hal_arch.h. If changes are required
# remember to update both sets.

#define CYGARC_JMP_BUF_R4        0
#define CYGARC_JMP_BUF_R5        2
#define CYGARC_JMP_BUF_A12       4
#define CYGARC_JMP_BUF_A13       8
#define CYGARC_JMP_BUF_A14      12
#define CYGARC_JMP_BUF_A15      16

#define CYGARC_JMP_BUF_SIZE     20

// FIXME: The follwing restricts us to using only 32 bit registers
// in jump buffers. If/when we move to a full 64 bit architecture,
// this will need to change, as will the instructions that we use to
// save and restore them.

#define jmpbuf_regsize 4
        
        .globl  hal_setjmp
hal_setjmp:
        ldw     a8,@[sp+2]      // jmpbuf
        ldw     @[a8+0],r4
        ldw     @[a8+2],r5
        ldw     @[a8+4],a12
        ldw     @[a8+8],a13
        ldw     @[a8+12],a14
        ldw     @[a8+16],a15
        retd
         ld     r0,#0
        .end hal_setjmp

        .globl  hal_longjmp
hal_longjmp:    
        ldw     a8,@[sp+2]
        ldw     r0,@[sp+6]
        ldw     r4,@[a8+0]
        ldw     r5,@[a8+2]
        ldw     a12,@[a8+4]
        ldw     a13,@[a8+8]
        ldw     a14,@[a8+12]
        ldw     a15,@[a8+16]
        and     r0,r0
        retd
        incc    r0
        .end hal_longjmp
        
        
#------------------------------------------------------------------------------
# end of context.S